In diesel engines, since a large quantity of exhaust-gas particle is discharged, the idea has been proposed to provide a filter for preventing the discharge of the particles into the atmosphere, and the particles are collected by the filter. However, with respect to the filter, the ventilating resistance of the filter is increased as the accumulation of the particles on the surface of the filter progresses so that means is employed to heat the collected particles and to burn and remove them whereby the filter is regenerated.
As a heating means for the regeneration of the filter, such a means was described, for example, in the official gazette of Japanese Patent Laid-open Publication No. 58-124618 as prior art literature which was adopted to elevate the temperature of exhaust gas and also to raise the HC density.
This prior art literature described the means for delaying the fuel injection period and then to burn it thereby to elevate the temperature of exhaust gas but the delay occurred on all the cylinders so that there was a drawback of a large reduction of output in the operation of regeneration of the filter. Also, although this prior art could be applied to a distributor type fuel injection pump, there was a drawback that it could not be applied to an in-line pump.